Core-shell Au@PdNPs based colorimetric enhanced lateral flow immunoassay for C-reactive protein detection

Benefiting from many advantages including low cost, simple operation and low dependence on analytical instruments, lateral flow immunoassay (LFIA) has been widely used in many fields such as food detection, environmental monitoring, disease diagnosis, etc., but the lack of sensitivity is still the main problem to be solved. Here, a simply prepared core-shell Au@PdNPs was used to displace the commonly used AuNPs to construct the colorimetric enhanced LFIA. As a label with high peroxidase-like activity, Au@PdNPs can further catalyze the oxidation and color conversion of TMB to obtain more significant visual signals. By using a high-viscosity chromogenic agent to reduce the diffusion and migration of colored products, another problem affecting the observation of testing results was also well solved. As a result, in the case of detecting C-reactive protein with important clinical diagnostic value, the limit of detection (0.32 ng/mL) was improved by about 62 times through additional 30 s of coloration. Considering its good performance in the detection of serum-containing samples, the proposed colorimetric enhanced LFIA provides an effective means for sensitive detection of low-concentration targets, which is worthy of further promotion and will play an important role in more clinical diagnostics.